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Dosimetric determination of tissue maximum ratios in small fields

Published online by Cambridge University Press:  06 April 2018

Qurat-ul-ain Shamsi ,
Saeed Ahmad Buzdar ,
Atia Atiq ,
Maria Atiq ,
Saima Altaf  and
Khalid Iqbal
Qurat-ul-ain Shamsi*
Affiliation:
Physics Department, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
Saeed Ahmad Buzdar
Affiliation:
Physics Department, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
Atia Atiq
Affiliation:
Physics Department, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
Maria Atiq
Affiliation:
Physics Department, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
Saima Altaf
Affiliation:
Physics Department, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
Khalid Iqbal
Affiliation:
Clinical & Radiation Oncology Department, Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, Punjab, Pakistan
*
Author for correspondence: Qurat-ul-ain Shamsi, Physics Department, The Islamia University of Bahawalpur, Bahawalpur 63100, Punjab, Pakistan. Tel: +92622875063;E-mail: annieshamsi86@gmail.com
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Abstract

Aims

This exploration is intended to measure tissue maximum ratios (TMRs) in smaller fields through CC01 detector and to compare CC01 measured TMRs with Pinnacle treatment planning software (TPS) calculated TMRs.

Materials and methods

CC01 compact chamber detector was used to measure TMR in water phantom for 6 and 18 MV beam delivered from Varian linear accelerator. Pinnacle TPS was employed in this study to calculate TMR from the measured percentage depth doses data. CC01 measured TMR data was compared with the calculated TMR data at depths from 5 to 20 cm for field sizes varying from 1 to 10 cm2.

Results

For the smallest given field size of 1 cm2, CCO1 measured 13·95% higher TMR value for 18 MV beam than that for 6 MV beam. At 20 cm depth for 1 cm2 field size, TMR due to 18 MV beam was 52·4% higher than the TMR due to 6 MV beam. For 6 MV beam, the maximum difference appeared between the measured TMR and pinnacle calculated TMR was 2·8% and for 18 MV beam, the maximum difference was 4%.

Conclusion

For both 6 and 18 MV beam, there was good agreement between CC01 measured and Pinnacle calculated TMRs for the field sizes ranging from 1 to 10 cm2. This exploration can be extended to the determination of other dosimetric parameters like TARs, TPRs in small fields.

Keywords

6 and 18 MV photon beamcompact chamber detector CC01Pinnacle treatment planning softwaresmall field dosimetrytissue maximum ratios
Type
Original Article
Information
Journal of Radiotherapy in Practice , Volume 17 , Issue 3 , September 2018 , pp. 289 - 291
Copyright
© Cambridge University Press 2018 

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