Radiation-induced complications in prostate cancer patients treated with radiotherapy

Azuddin, A. Yusof; Rahman, I. Abdul; Siah, N. J.; Mohamed, Faheez; Saadc, M.; Ismail, Fuad

doi:10.1063/1.4895181

Cited by 2 publications

(2 citation statements)

References 16 publications

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“…With an exception of degraded HI and lower MUs, the results of Part 1 of this study are in agreement with a previous study [100], which compared dosimetric quality of single-energy partial-arc (30 0 -165 0 and 195 0 -330 0 ) VMAT plans with that of a single-energy full-arc (0 0 -359 0 ) VMAT plans for prostate and demonstrated that partial-arcs technique results in lower doses to the bladder and rectum but at an expense of higher doses to femoral heads [ Furthermore, it has been reported that dose ≥ 78 Gy to 50% of the bladder volume results in the development of GU complications [116], which was not exceeded by any of the plans in this study. It is important to note here that maximum dose to bladder exceeded 65 Gy, especially in the overlapping region of bladder and the PTV, which involves the risk of Grade 3 toxicity as a late response [105].…”

Section: Discussionmentioning

confidence: 99%

On Optimization of Mixed Photon Energies in Volumetric Modulated Arc Therapy

Momin¹

2023

Preprint

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This dissertation investigates the dosimetric influence of mixed photon beams in volumetric modulated arc therapy (VMAT) for prostate cancer and presents new algorithmic frameworks for simultaneous optimization of mixed photon beams in VMAT. The potential scope of using mixed photon VMAT for prostate cancer was first studied by using a clinical treatment planning software. A significant reduction in doses to bladder (P < 0.05) and rectum (P < 0.05), and similar target dose conformity was achieved by mixed photon (6&15 MV) VMAT compared to single energy (6 or 15 MV) VMAT. Radiobiological effectiveness was evaluated through tumor control probability (TCP) and normal tissue complication probability (NTCP). Across four different parameter sets for grade ≥ 2 rectal bleeding, mixed energy reduced NTCP by 1.3%, 4.1%, 0.1% and 2.6%, respectively, compared to single energy (P < 0.05). For bladder, mixed energy reduced mean equivalent uniform dose by 2 Gy (P < 0.05). In this study, however, each energy plan had to be optimized separately followed by their summation in order to generate a mixed photon VMAT plan. From optimization standpoint, this approach limits the solution search space. With the aim of furthering current optimization approach, a comprehensive algorithmic framework was presented for simultaneous optimization of mixed photon beams (6 & 18 MV) in VMAT (MP-VMAT). This was solved heuristically in two steps, accounting for dosimetric and mechanical constraints. This novel proof of concept was tested for its practicality and dosimetric outcome on two prostate cancer cases. In both cases, the proposed approach was able to reduce doses to rectum and bladder while maintaining the target dose coverage. Overall results suggested the viability and dosimetric benefits of the proposed concept, compared to single energy approach, in VMAT planning. Next, the concept of MP-VMAT was expanded for a single-arc treatment, consisting of energy dependent partial arcs. To this end, the first formalism was presented to optimize mixed photon energy (6 & 18 MV) fluences along with corresponding arc locations and lengths over a full 360o gantry rotation. The radiobiological and dosimetric effectiveness of this framework was tested on prostate cases with varying body types. The proposed technique was able to reduce bladder and rectum complication by 14% and 7%, respectively, in large size patients compared to single energy VMAT. The novel concept of simultaneous optimization of multi-energy introduced in this dissertation can also be employed in learning based approach for beam angle optimization in intensity modulated radiation therapy treatments as well as in optimization of mixed modality treatments.

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Section: Discussionmentioning

confidence: 99%

On Optimization of Mixed Photon Energies in Volumetric Modulated Arc Therapy

Momin¹

2023

Preprint

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“…Furthermore, it has been reported that dose ≥78 Gy to 50% of the bladder volume results in the development of GU complications, which was not exceeded by any of the plans in this study. It is important to note here that maximum dose to bladder exceeded 65 Gy, especially in the overlapping region of bladder and the PTV, which involves the risk of Grade 3 toxicity as a late response .…”

Section: Discussionmentioning

confidence: 99%

Evaluation of mixed energy partial arcs for volumetric modulated arc therapy for prostate cancer

Momin

Gräfe

Khan

2019

J Applied Clin Med Phys

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Purpose The purpose of this work was to investigate the dosimetric impact of mixed energy (6‐MV, 15‐MV) partial arcs (MEPAs) technique on prostate cancer VMAT plans. Methods This work involved prostate only patients, planned with 79.2 Gy in 44 fractions to the planning target volume (PTV). Femoral heads, bladder, and rectum were considered organs at risk. This study was performed in two parts. For each of the 25 patients in Part 1, two single‐energy single‐arc plans, a 6 MV‐SA plan and a 15 MV‐SA plan, and a third MEPA plan involving composite of 6‐MV anterior–posterior partial arcs and a 15‐MV lateral partial arc weighted 1:2 were created. The dosimetric difference between MEPA(6/15 MV 1:2 weighted) and 6 MV‐SA plans, and MEPA(6/15 MV 1:2 weighted) and 15 MV‐SA plans were measured. In the Part 2 of this study, a second MEPAs plan (6 MV anterior–posterior arcs and 15 MV lateral arcs weighted 1:1), (MEPA 6/15 MV 1:1 weighted), was generated for 15 patients and compared only with two single‐energy partial arcs plans, a 6 and a 15 MV‐PA, to investigate the influence of the energy only. Dosimetric parameters of each structure, total monitor‐units (MUs), homogeneity index (HI), and conformity number (CN) were analyzed. Results In Part 1, no statistically significant differences were observed for mean dose to PTV and CN for MEPAs (6/15 MV 1:2 weighted) vs 6 and 15 MV‐SA. MEPAs (6/15 MV 1:2 weighted) increased HI compared to 6 and 15 MV‐SA (P < 0.0005; P < 0.0005). MEPAs (6/15 MV 1:2 weighted) produced significantly lower mean doses to rectum, bladder, and MUs/fraction, but higher mean doses to femoral heads, compared to 6 MV‐SA (P < 0.0005) and 15 MV‐SA (P < 0.0005). The results of Part 2 of this study showed that, in comparison to 6 and 15 MV‐PA, MEPAs (6/15 MV 1:1 weighted) plans significantly improved CNs (P < 0.0005; P < 0.0005) and produced significantly lower mean doses to the rectum and bladder (P < 0.0005; P < 0.0005). While mean doses to the PTV and femoral heads of MEPAs (6/15 MV 1:1 weighted) plans were statistically comparable to 6 MV‐PA (P > 0.05), MEPAs (6/15 MV 1:1 weighted) increased mean doses to left (P = 0.04) and right (P = 0.04) femoral heads compared to 15 MV‐PA. MEPAs (6/15 MV 1:1 weighted) resulted in significantly lower total MUs compared to 6 MV‐PA (P < 0.0005) and 15 MV‐PA (P = 0.04). Conclusion The study for prostate radiotherapy demonstrated that a choice of MEPAs for VMAT has the potential to minimize doses to OARs and improve dose conformity to PTV, at the expense of a moderate increase in mean dose to the femoral heads.

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Radiation-induced complications in prostate cancer patients treated with radiotherapy

Cited by 2 publications

References 16 publications

On Optimization of Mixed Photon Energies in Volumetric Modulated Arc Therapy

On Optimization of Mixed Photon Energies in Volumetric Modulated Arc Therapy

Evaluation of mixed energy partial arcs for volumetric modulated arc therapy for prostate cancer

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