Abstract
Contrast materials help in contouring in radiotherapy. The primary aim of this study is to investigate the effects of contrast materials in bladder on the dosimetry during prostate intensity modulated radiation therapy and volumetric modulated arc therapy. The study also investigates the difference of the two dose calculation options namely ‘dose to medium (Dm)’ and ‘dose to water (Dw)’ in a commercial Monte Carlo based treatment planning system. Eight IMRT treatment plans were retrospectively studied which were used to treat high risk prostate cancer patients. The treatment plans generated in Monaco treatment planning system use seven coplanar beams and calculated ‘Dm’ as the clinical option. These plans were recalculated, keeping the segments, beam angle and monitor units the same, with different relative electron densities assigned to the structure ‘bladder’ to mimic the presence of contrast material. The same plans were recalculated using the ‘Dw’ option. Further, keeping the IMRT constraints and plan calculation properties the same, these plans were re-optimised with the delivery method changed to volumetric modulated arc therapy and calculated using both ‘Dm’ and ‘Dw’ options. For all the four scenarios, it was found that for the target volumes CTV and PTV, ‘minimum dose’ is the only endpoint studied having a significant difference with the presence of contrast material. For bladder, the endpoint V40 Gy is affected. Any significant dosimetric effect is found only when the relative electron density of the contrast material is 1.2 or more. Also, the dosimetric difference is greater when ‘Dm’ option is used for calculation. For rectum, the dosimetry remains unaffected. Hence, contrast materials should be contoured and assigned appropriate relative electron densities during IMRT and VMAT treatment planning of prostate. Also, the difference in dose reported with the two dose calculation options (Dm and Dw) in the presence of contrast materials is significant.
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References
Rankine AW, Lanzon PJ, Spry NA (2008) Effect of contrast media on megavoltage photon beam dosimetry. Med Dosim 33(3):169–174
Gleeson I (2013) Dosimetric effects of bladder and rectal contrast agents in prostate radiotherapy. J Radiother Pract 12(4):344–351
ICRU (1993) International Commission on Radiation Units and Measurements. Prescribing, recording and reporting photon beam therapy. ICRU Report 50 (International Commission on Radiation Units and Measurements, Bethesda)
ICRU (1999) International Commission on Radiation Units and Measurements. Prescribing, recording and reporting photon beam therapy supplement to ICRU Report 50). ICRU Report 62 (International Commission on Radiation Units and Measurements, Bethesda)
Report of the AAPM Task Group No. 105 (2007) Issues associated with clinical implementation of Monte Carlo-based photon and electron external beam treatment planning. Med Phys 34(12):4818–4853
Usmani MN, Masai N, Oh RJ, Shiomi H, Tatsumi D, Miura H, Inoue T, Koizumi M (2014) Comparison of absorbed dose to medium and absorbed dose to water for spine IMRT plans using a commercial Monte Carlo treatment planning system. Int J Med Phys Clin Eng Radiat Oncol 3:60–66
Siebers JV, Keall PJ, Nahum AE, Mohan R (2000) Converting absorbed dose to medium to absorbed dose to water for Monte Carlo based photon beam dose calculations Phys. Med Biol 45:983–995
Keall PJ (2002) Dm rather than Dw should be used in monte carlo treatment planning. Against the proposition. Med Phys 29(5):923–924
Ma CM, Mok E, Kapur A (1999) Clinical implementation of a monte carlo treatment planning system. Med Phys 26(10):2133–2143
Solberg TD, DeMarco JJ, Holly FE, Smathers JB, DeSalles AAF (1998) Monte Carlo treatment planning for stereotactic radiosurgery. Radiother Oncol 49(1):73–84
Ma CM, Pawlicki T, Jiang SB (2000) Monte Carlo verification of IMRT dose distributions from a commercial treatment planning optimization system. Phys Med Biol 45(9):2483–2495
Monaco external beam dose calculation algorithms technical reference V1.0 (2014)
Fippel M (1999) Fast Monte Carlo dose calculation for photon beams based on the VMC electron algorithm. Med Phys 26:1466
Grofsmid D, Dirkx M, Marijnissen H, Woudstra E, Heijmen B (2010) Dosimetric validation of a commercial Monte Carlo based IMRT planning system. Med Phys 37:540
Walters BRB, Kramer R, Kawrakow I (2010) Dose to medium versus dose to water as an estimator of dose to sensitive skeletal tissue. Phys Med Biol 55(2010):4535–4546
Dogan N, Siebers JV, Keall PJ (2006) Clinical comparison of head and neck and prostate IMRT plans using absorbed dose to medium and absorbed dose to water. Phys Med Biol 51(2006):4967–4980
Report No.83 of the ICRU, (2010) Prescribing, recording and reporting photon-beam intensity modulated radiation therapy (IMRT), J ICRU 10(1)
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Mundayadan Chandroth, M., Venning, A., Chick, B. et al. Effects of contrast materials in IMRT and VMAT of prostate using a commercial Monte Carlo algorithm. Australas Phys Eng Sci Med 39, 547–556 (2016). https://doi.org/10.1007/s13246-016-0427-0
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DOI: https://doi.org/10.1007/s13246-016-0427-0