Assessment of Peripheral Dose As a Function of Distance and Depth from Cobalt-60 Beam in Water Phantom Using TLD-100

Overview

Journal J Egypt Natl Canc Inst

Specialty Oncology

Date 2024 Jun 23

PMID 38910202

Authors

Habib Ahmad

Javaid Ali

Khalil Ahmad

Ghufran Biradar

Ashfaq Zaman

Yasir Uddin

Muhammad Sohail

Shahid Ali

Affiliations

Soon will be listed here.

Abstract

Background: Innovations in cancer treatment have contributed to the improved survival rate of cancer patients. The cancer survival rates have been growing and nearly two third of those survivors have been exposed to clinical radiation during their treatment. The study of long-term radiation effects, especially secondary cancer induction, has become increasingly important. An accurate assessment of out-of-field/peripheral dose (PDs) is necessary to estimate the risk of second cancer after radiotherapy and the damage to the organs at risk surrounding the planning target volume. This study was designed to measure the PDs as a function of dose, distances, and depths from Telecobalt-60 (Co-60) beam in water phantom using thermoluminescent dosimeter-100 (TLD-100).

Methods: The PDs were measured for Co-60 beam at specified depths of 0 cm (surface), 5 cm, 10 cm, and 15 cm outside the radiation beam at distances of 5, 10, and 13 cm away from the radiation field edge using TLD-100 (G1 cards) as detectors. These calibrated cards were placed on the acrylic disc in circular tracks. The radiation dose of 2000 mGy of Co-60 beam was applied inside 10 × 10 cm field size at constant source to surface distance (SSD) of 80 cm.

Results: The results showed maximum and minimum PDs at surface and 5 cm depth respectively at all distances from the radiation field edge. Dose distributions out of the field edge with respect to distance were isotropic. The decrease in PDs at 5 cm depth was due to dominant forward scattering of Co-60 gamma rays. The increase in PDs beyond 5 cm depth was due to increase in the irradiated volume, increase in penumbra, increase in source to axis distance (SAD), and increase in field size due to inverse square factor.

Conclusion: It is concluded that the PDs depends upon depth and distance from the radiation field edge. All the measurements show PDs in the homogenous medium (water); therefore, it estimates absorbed dose to the organ at risk (OAR) adjacent to cancer tissues/planning target volume (PTV). It is suggested that PDs can be minimized by using the SAD technique, as this technique controls sources of scattered radiation like inverse square factor and effect of penumbra up-to some extent.

References

Dracham C, Shankar A, Madan R . Radiation induced secondary malignancies: a review article. Radiat Oncol J. 2018; 36(2):85-94. PMC: 6074073. DOI: 10.3857/roj.2018.00290. View

Taddei P, Khater N, Zhang R, Geara F, Mahajan A, Jalbout W . Inter-Institutional Comparison of Personalized Risk Assessments for Second Malignant Neoplasms for a 13-Year-Old Girl Receiving Proton versus Photon Craniospinal Irradiation. Cancers (Basel). 2015; 7(1):407-26. PMC: 4381265. DOI: 10.3390/cancers7010407. View

Van Der Giessen P . Peridose, a software program to calculate the dose outside the primary beam in radiation therapy. Radiother Oncol. 2001; 58(2):209-13. DOI: 10.1016/s0167-8140(00)00326-1. View

Vlachopoulou V, Malatara G, Delis H, Theodorou K, Kardamakis D, Panayiotakis G . Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET. World J Radiol. 2010; 2(11):434-9. PMC: 3006482. DOI: 10.4329/wjr.v2.i11.434. View

Brenner D, Doll R, Goodhead D, Hall E, Land C, Little J . Cancer risks attributable to low doses of ionizing radiation: assessing what we really know. Proc Natl Acad Sci U S A. 2003; 100(24):13761-6. PMC: 283495. DOI: 10.1073/pnas.2235592100. View

Dorr W, Herrmann T . Cancer induction by radiotherapy: dose dependence and spatial relationship to irradiated volume. J Radiol Prot. 2002; 22(3A):A117-21. DOI: 10.1088/0952-4746/22/3a/321. View

Brenner D, Curtis R, Hall E, Ron E . Second malignancies in prostate carcinoma patients after radiotherapy compared with surgery. Cancer. 2000; 88(2):398-406. DOI: 10.1002/(sici)1097-0142(20000115)88:2<398::aid-cncr22>3.0.co;2-v. View

Brenner D, Sachs R . Estimating radiation-induced cancer risks at very low doses: rationale for using a linear no-threshold approach. Radiat Environ Biophys. 2006; 44(4):253-6. DOI: 10.1007/s00411-006-0029-4. View

Shahban M, Hussain B, Mehmood K, Rehman S . Estimation of peripheral dose from Co beam in water phantom measured in Secondary Standard Dosimetry Laboratory, Pakistan. Rep Pract Oncol Radiother. 2017; 22(3):212-216. PMC: 5403798. DOI: 10.1016/j.rpor.2016.12.002. View

10.

McParland B, Fair H . A method of calculating peripheral dose distributions of photon beams below 10 MV. Med Phys. 1992; 19(2):283-93. DOI: 10.1118/1.596858. View

11.

Ruben J, Lancaster C, Jones P, Smith R . A comparison of out-of-field dose and its constituent components for intensity-modulated radiation therapy versus conformal radiation therapy: implications for carcinogenesis. Int J Radiat Oncol Biol Phys. 2010; 81(5):1458-64. DOI: 10.1016/j.ijrobp.2010.08.008. View

12.

Stovall M, Blackwell C, Cundiff J, Novack D, Palta J, Wagner L . Fetal dose from radiotherapy with photon beams: report of AAPM Radiation Therapy Committee Task Group No. 36. Med Phys. 1995; 22(1):63-82. DOI: 10.1118/1.597525. View

13.

Sanchez-Nieto B, Medina-Ascanio K, Rodriguez-Mongua J, Doerner E, Espinoza I . Study of out-of-field dose in photon radiotherapy: A commercial treatment planning system versus measurements and Monte Carlo simulations. Med Phys. 2020; 47(9):4616-4625. PMC: 7586840. DOI: 10.1002/mp.14356. View

14.

Howell R, Scarboro S, Kry S, Yaldo D . Accuracy of out-of-field dose calculations by a commercial treatment planning system. Phys Med Biol. 2010; 55(23):6999-7008. PMC: 3152254. DOI: 10.1088/0031-9155/55/23/S03. View

15.

Schneider U . Modeling the risk of secondary malignancies after radiotherapy. Genes (Basel). 2014; 2(4):1033-49. PMC: 3927608. DOI: 10.3390/genes2041033. View

16.

Hall E, Wuu C . Radiation-induced second cancers: the impact of 3D-CRT and IMRT. Int J Radiat Oncol Biol Phys. 2003; 56(1):83-8. DOI: 10.1016/s0360-3016(03)00073-7. View

17.

Hauri P, Halg R, Besserer J, Schneider U . A general model for stray dose calculation of static and intensity-modulated photon radiation. Med Phys. 2016; 43(4):1955. DOI: 10.1118/1.4944421. View

18.

Schneider C, Newhauser W, Wilson L, Kapsch R . A physics-based analytical model of absorbed dose from primary, leakage, and scattered photons from megavoltage radiotherapy with MLCs. Phys Med Biol. 2019; 64(18):185017. DOI: 10.1088/1361-6560/ab303a. View

19.

Wilson L, Newhauser W, Schneider C, Kamp F, Reiner M, Martins J . Method to quickly and accurately calculate absorbed dose from therapeutic and stray photon exposures throughout the entire body in individual patients. Med Phys. 2020; 47(5):2254-2266. DOI: 10.1002/mp.14018. View

20.

Adams E, Warrington A . A comparison between cobalt and linear accelerator-based treatment plans for conformal and intensity-modulated radiotherapy. Br J Radiol. 2008; 81(964):304-10. DOI: 10.1259/bjr/77023750. View