Verification of nose irradiation using orthovoltage x-ray beams

Currie, Michael; Bailey, Michael; Butson, Martin J

doi:10.1007/bf03178414

Cited by 6 publications

(9 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Historically these have included MD-55 and HS film [6][7][8][9][10][11][12] , ISP's films designed specifically for radiotherapy applications where large doses (up to 30 Gy) are required, XR-R films [13][14][15] for high dose diagnostic imaging applications through to films such as XRQA [16][17] which is designed for low dose assessment at kilovoltage x-ray energies. Probably the most used film for radiation dosimetry in therapy applications has been Gafchromic EBT film [18][19][20][21][22][23][24] . Its properties have included lowest energy dependence of any film type dosimeter, radiation sensitivity matched to therapy applications (1-2Gy), flexibility and easy analysis with a common desktop scanner.…”

Section: Introductionmentioning

confidence: 99%

Dose and absorption spectra response of EBT2 Gafchromic film to high energy x-rays

Butson

Cheung

et al. 2009

Australas. Phys. Eng. Sci. Med.

View full text Add to dashboard Cite

With new advancements in radiochromic film designs and sensitivity to suit different niche applications, EBT2 is the latest offering for the megavoltage radiotherapy market. New construction specifications including different physical construction and the use of a yellow coloured dye has provided the next generation radiochromic film for therapy applications. The film utilises the same active chemical for radiation measurement as its predecessor, EBT Gafchromic. Measurements have been performed using photo spectrometers to analyse the absorption spectra properties of this new EBT2 Gafchromic, radiochromic film. Results have shown that whilst the physical coloration or absorption spectra of the film, which turns yellow to green as compared to EBT film, (clear to blue) is significantly different due to the added yellow dye, the net change in absorption spectra properties for EBT2 are similar to the original EBT film. Absorption peaks are still located at 636nm and 585nm positions. A net optical density change of 0.590 +/- 0.020 (2SD) for a 1 Gy radiation absorbed dose using 6 MV x-rays when measured at the 636nm absorption peak was found. This is compared to 0.602 +/- 0.025 (2SD) for the original EBT film (2005 Batch) and 0.557 +/- 0.027 (2009 Batch) at the same absorption peak. The yellow dye and the new coating material produce a significantly different visible absorption spectra results for the EBT2 film compared to EBT at wavelengths especially below approximately 550nm. At wavelengths above 550nm differences in absolute OD are seen however, when dose analysis is performed at wavelengths above 550nm using net optical density changes, no significant variations are seen. If comparing results of the late production EBT to new production EBT2 film, net optical density variations of approximately 10 % to 15 % are seen. As all new film batches should be calibrated for sensitivity upon arrival this should not be of concern.

show abstract

Section: Introductionmentioning

confidence: 99%

Dose and absorption spectra response of EBT2 Gafchromic film to high energy x-rays

Butson

Cheung

et al. 2009

Australas. Phys. Eng. Sci. Med.

View full text Add to dashboard Cite

show abstract

“…Dosimetric challenges from the nose contour have been recognized in the literature. Currie et al (2007) conducted a dosimetric study on a nose phantom using both single anterior field and laterally opposed approach [ 9 ]. In their study, there is a significant dose drop off from depth of 6.5 mm to 21.5 mm, from 84% to 50%, respectively [ 9 ].…”

Section: Discussionmentioning

confidence: 99%

“…However, treatment of such cancers of the face, particularly on the nose, can be challenging. Traditionally, nonmelanoma skin cancers in this location are treated with a single anterior field using ortho-Voltage or electron beam radiation [ 9 ]. However, delivering a homogeneous dose to the target can often be difficult due to the contour variability.…”

Section: Introductionmentioning

confidence: 99%

“…An approach that could potentially minimize unnecessary exposure of underlying structures to radiation would be to treat the lesion laterally with two parallel opposed (POP) fields. Despite using opposing lateral fields, dose homogeneity remains challenging due to the contour of the nasal region [ 9 ]. To mitigate this, we typically used a customized rectangular nose bolus.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optical scan and 3D printing guided radiation therapy – an application and provincial experience in cutaneous nasal carcinoma

et al. 2022

View full text Add to dashboard Cite

Background Single field Orthovoltage radiation is an acceptable modality used for the treatment of nasal cutaneous cancer. However, this technique has dosimetric pitfalls and unnecessary excessive exposure of radiation to organs at risk (OAR). We present the clinical outcome of a case series of cutaneous nasal tumours using a novel technique incorporating an optical scanner and a 3-dimensional (3D) printer to deliver treatments using parallel opposed (POP) fields. Materials and methods The POP delivery method was validated using ion chamber and phantom measurements before implementation. A retrospective chart review of 26 patients treated with this technique between 2015 and 2019 was conducted. Patients’ demographics and treatment outcomes were gathered and tabulated. These patients first underwent an optical scan of their faces to collect topographical data. The data were then transcribed into 3D printing algorithms, and positive impressions of the faces were printed. Custom nose block bolus was made with wax encased in an acrylic shell; 4 cm thick using the printed face models. Custom lead shielding was also generated. Treatments were delivered using 250 KeV photons POP arrangement with 4 cm diameter circle applicator cone and prescribed to the midplane. Dose and fractionation were as per physician discretion. Results Phantom measurements at mid-plane were found to match the prescribed dose within ±0.5%. For the 26 cases in this review, the median age was 78.5 years, with 15 females and 11 males. 85% of cases had Basal cell carcinoma (BCC); 1 had squamous cell carcinoma (SCC), one had synchronous BCC + SCC, and 1 had Merkel cell carcinoma. Twenty-one cases had T1N0 disease, 4 had T2N0, and 1 had T3N0. Dose and fractionation delivered were 40Gy in 10 fractions for the majority of cases. The complete response rate at a median follow-up of 6 months was 88%; 1 patient had a refractory tumour, and one patient had a recurrence. Toxicities were minor with 81% with no reported side effects. Three patients experienced grade 3 skin toxicity. Conclusions Utilization of optic scanner and 3D printing technology, with the innovative approach of using POP orthovoltage beams, allows an effective and efficient way of treatment carcinomas of the nose with a high control rate and low toxicity profiles.

show abstract

“…The low X-ray energy dependence of radiochromic films [1,2] make them clinically useful in both kilovoltage X-ray applications [3][4][5][6][7] and high energy X-ray applications [8][9][10][11]. Radiochromic films that are commonly used in these applications include Gafchromic EBT and EBT2 films.…”

Section: Introductionmentioning

confidence: 99%

Scanner uniformity improvements for radiochromic film analysis with matt reflectance backing

Butson¹,

Alnawaf

et al. 2011

Australas Phys Eng Sci Med

View full text Add to dashboard Cite

A simple and reproducible method for increasing desktop scanner uniformity for the analysis of radiochromic films is presented. Scanner uniformity, especially in the non-scan direction, for transmission scanning is well known to be problematic for radiochromic film analysis and normally corrections need to be applied. These corrections are dependant on scanner coordinates and dose level applied which complicates dosimetry procedures. This study has highlighted that using reflectance scanning in combination with a matt, white backing material instead of the conventional gloss scanner finish, substantial increases in the scanner uniformity can be achieved within 90% of the scanning area. Uniformity within ±1% over the scanning area for our epsonV700 scanner tested was found. This is compared to within ±3% for reflection scanning with the gloss backing material and within ±4% for transmission scanning. The matt backing material used was simply 5 layers of standard quality white printing paper (80 g/m(2)). It was found that 5 layers was the optimal result for backing material however most of the improvements were seen with a minimum of 3 layers. Above 5 layers, no extra benefit was seen. This may eliminate the need to perform scanner corrections for position on the desktop scanners for radiochromic film dosimetry.

show abstract

Verification of nose irradiation using orthovoltage x-ray beams

Cited by 6 publications

References 16 publications

Dose and absorption spectra response of EBT2 Gafchromic film to high energy x-rays

Dose and absorption spectra response of EBT2 Gafchromic film to high energy x-rays

Optical scan and 3D printing guided radiation therapy – an application and provincial experience in cutaneous nasal carcinoma

Scanner uniformity improvements for radiochromic film analysis with matt reflectance backing

Contact Info

Product

Resources

About