Highlights
- •In IMPT, the minimum dose to PTV does not represent the minimum dose to CTV.
- •OAR DVH underestimates OAR dose receiving under geometrical uncertainties.
- •OAR DVH does not match any confidence levels from Dose Volume Population Histogram.
- •Dose Volume Population Histogram tool helps planners evaluate the plans reliably.
Abstract
Purpose
Under geometrical uncertainties, different plan evaluation methods have been suggested
but the dose distribution at a specified confidence level being highly desirable is
lacking. In this work, we used the DVPH (Dose Volume Population Histogram) tool to
evaluate the dose distribution of CTVs and OARs (Organs at Risk) and validate the
PTV concept at a certain confidence level.
Methods
The plans were evaluated using PTV DVH and the DVPH approach. The DVPH approach is
based on statistical analyzing of multiple CTV DVHs under geometrical errors with
corresponding occurring probabilities. The random and systematic geometrical errors,
assumed to follow a Gaussian distribution, are simulated by shifting the CT images.
Results
For target doses, the results showed that the minimum dose to PTV does not represent
the minimum dose to the CTV. For two prostate cases, the minimum doses reduced from
98% and 95% of prescribed dose from PTV DVH to 89% and 92% of prescribed dose from
CTV 90% CL-DVPH (90% Confidence Level-DVPH). This reduction was also seen in head
and neck cases, from 95% to 68% and 74% of prescribed dose. For OAR doses, OAR DVHs
underestimated the OAR dose receiving.
Conclusions
With the DVPH tool, the results showed that the minimum dose to the PTV is not a representative
of the minimum dose to the CTV in IMPT at the 90% confidence level. The OAR DVH does
not match any OAR CL-DVPHs.
Keywords
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References
International Commission on Radiation Units and Measurements. Prescribing, Recording and Reporting Photon Beam Therapy. ICRU Report 50. Bethesda, MD: ICRU, 1993.
- Inclusion of geometrical uncertainties in radiotherapy treatment planning by means of coverage probability.Int J Radiat Oncol Biol Phys. 1999; 43: 905-919
- The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy.Int J Radiat Oncol Biol Phys. 2000; 47: 1121-1135
- Margins for treatment planning of proton therapy.Phys Med Biol. 2006; 51: 1491-1501
- Intensity modulated proton therapy and its sensitivity to treatment uncertainties 2: the potential effects of inter-fraction and inter-field motions.Phys Med Biol. 2008; 53: 1043-1056
- Is it necessary to plan with safety margins for actively scanned proton therapy?.Phys Med Biol. 2011; 56: 4399-4413
- A novel method for the evaluation of uncertainty in dose-volume histogram computation.Int J Radiat Oncol Biol Phys. 2008; 70: 1263-1271
- Statistical assessment of proton treatment plans under setup and range uncertainties.Int J Radiat Oncol Biol Phys. 2013; 86: 1007-1013
- Dose-volume population histogram: a new tool for evaluating plans whilst considering geometrical uncertainties.Phys Med Biol. 2009; 54: 935-947
- Initial results of a phase 3 randomized study of high dose 3DCRT/IMRT versus standard dose 3D-CRT/IMRT in patients treated for localized prostate cancer (RTOG 0126).Int J Radiat Oncol Biol Phys. 2014; 90: 1263
- Intensity-modulated radiation therapy with or without chemotherapy for nasopharyngeal carcinoma: radiation therapy oncology group phase II trial 0225.J Clin Oncol. 2009; 27: 3684-3690
- Radiation therapy oncology group (RTOG) Protocol 0623: a phase II trial of combined modality therapy with growth factor support for patients with limited stage small cell lung.Cancer. 2008;
- Advanced treatment planning methods for efficient radiation therapy with laser accelerated proton and ion beams.Med Phys. 2010; 37: 5330-5340
- CERR: a computational environment for radiotherapy research.Med Phys. 2003; 30: 979-985
- A pencil beam algorithm for proton dose calculations.Phys Med Biol. 1996; 41: 1305-1330
- Multiple Coulomb scattering of 160 MeV protons.Nucl Instrum Meth Phys Res B. 1993; 74: 467-490
- A pencil beam algorithm for magnetic resonance image-guided proton therapy.Med Phys. 2018; 45: 2195-2204
- Fast pencil beam dose calculation for proton therapy using a double gaussian beam model.Front Oncol. 2015; 5: 281
- Sub-second pencil beam dose calculation on GPU for adaptive proton therapy.Phys Med Biol. 2015; 60: 4777-4795
- Impact of dose engine algorithm in pencil beam scanning proton therapy for breast cancer.Phys Med. 2018; 50: 7-12
- The impact of dose algorithms on tumor control probability in intensity-modulated proton therapy for breast cancer.Phys Med. 2019; 61: 52-57
Nutting CM, Bidmead M, Harrington KJ, Henkm JM. Geometric uncertainties in radiotherapy of head and neck. Geometric uncertainties in Radiotherapy (London:BIR) 2003:127-41.
- Quantification of shape variation of prostate and seminal vesicles during external beam radiotherapy.Int J Radiat Oncol Biol Phys. 2005; 61: 228-238
- Emptying the rectum before treatment delivery limits the variations of rectal dose – volume parameters during 3DCRT of prostate cancer.Radiother Oncol. 2006; 80: 363-370
- Quantification of local rectal wall displacements by virtual rectum unfolding.Radiother Oncol. 2004; 70: 21-30
- A method to calculate coverage probability from uncertainties in radiotherapy via a statistical shape model.Phys Med Biol. 2007; 52: 1947-1965
Article info
Publication history
Published online: September 14, 2019
Accepted:
September 5,
2019
Received in revised form:
August 26,
2019
Received:
June 10,
2019
Identification
Copyright
© 2019 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
