Evidence map›Paper›PMID 36106986›Full record

ArticleJournal of applied clinical medical physics2022

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry.

Hamed Hooshangnejad, Dong Han, Ziwei Feng, Liang Dong, Edward Sun, Kaifang Du, Kai Ding

Open access · goldAbstract read
In one paragraph

Article in Journal of applied clinical medical physics, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.

0numbers the graph read from it
0cells of the map it votes in
5citing papers in PubMed
0.8field-weighted citation impact, top 28% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

5 citing papers in PubMed, 5 citations in OpenAlex.

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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

7 authors at 3 institutions in 2 countries.

Hamed HooshangnejadDepartment of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Dong HanDepartment of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Ziwei FengDepartment of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Liang DongDepartment of Urology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Edward SunDepartment of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Kaifang DuTexas Center for Proton Therapy, Irving, TX, USA.
Kai DingDepartment of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Johns Hopkins Medicine · USJohns Hopkins University · USProvision Center for Proton Therapy · US

Funding

Spacer Enabled Robust Radiation Therapy (SERRT)R37CA229417 · NCI · JOHNS HOPKINS UNIVERSITY · PI DING, KAI · 2018 to 2021
$1.5M
National Cancer Institute of the National Institutes of Health R37CA229417NCI NIH HHS R37 CA229417
6 · The paper itself

Abstract

purposeIodination of rectal hydrogel spacer increases the computed tomography (CT) visibility. The effect of iodinated hydrogel spacer material on the accuracy of proton dosimetry has not been fully studied yet. We presented a systematic study to determine the effect of iodination on proton dosimetry accuracy during proton therapy (PT).

methodsPT plans were designed for 20 prostate cancer patients with rectal hydrogel spacer. Three variations of hydrogel density were considered. First, as the ground truth, the true elemental composition of hydrogel true material (TM), verified by our measurement of spacer stopping power ratio, was used for plan optimization and Monte Carlo dose calculation. The dose distribution was recalculated with (1) no material (NM) override based on the CT intensity of the iodinated spacer, and (2) the water material (WM) override, where spacer material was replaced by water. The plans were compared with the ground truth using the metrics of gamma index (GI) and dosimetric indices.

resultsThe iodination of hydrogel spacer affected the proton dose distribution with the NM scenario showing the most deviation from the ground truth. The iodination of spacer resulted in a notable increase in CT intensity and led to the treatment planning systems mistreating the iodinated spacer as a high-density material. Among the structures adjacent to the target, neurovascular bundles showed the largest dose difference, up to 350 cGy or about 5% of the prescribed dose with NM. Compared to the WM scenario, dose distribution similarity and GI passing ratios were lower in the NM scenario.

conclusionThe inaccurate CT intensity-based material for iodinated spacer resulted in errors in PT dose calculation. We found that the error was negligible if the iodinated spacer was replaced with water. Water density can be used as a clinically accessible and convenient alternative material override to true spacer material.

Indexed as

Prostatic NeoplasmsProton TherapyHumansHydrogelsMaleProtonsRadiometryRadiotherapy DosageRadiotherapy Planning, Computer-AssistedRectumWaterHydrogelsProtonsWaterhydrogel spacer iodinationneurovascular bundleproton dose discrepancyspacer-enabled proton therapy

Identifiers

PMID36106986
PMCPMC9588264
OpenAlexW4295904504

What OpenQuestion holds

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LicenceCC BY
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.