A test system and method for the effect of iodized oil area on photon radiotherapy dose

Abstract

The present invention relates to the field of clinical radiotherapy technology, and in particular to a test system and method for the effect of an iodized oil area on photon radiotherapy dose. The system comprises: a plurality of iodized oil samples, each of which is made by mixing minced pig liver and iodized oil in different proportions; a cylindrical sample tube, each of which is composed of a plurality of detachably connected sample chambers, each of which is provided with the iodized oil samples in the sample chambers, each corresponding to the iodized oil sample. The linear accelerator irradiates an abdominal simulation phantom into which the sample tube is inserted. The CT scanner is connected to a radiotherapy planning system, which simulates the irradiation of the sample tube with a photon beam based on a CT image and obtains a simulated dose of electron density. The present application can characterize the effect of the iodized oil area on the photon radiotherapy dose by comparing the simulated dose of electron density obtained by the radiotherapy planning system with the actual dose of electron density obtained by an ionization chamber detector.

Description

Technical Field

[0001] The present invention relates to the technical field of clinical radiotherapy, and in particular to a test system and method for the influence of an iodized oil area on a photon radiotherapy dose. Background Art

[0002] After interventional surgery, iodized oil is specifically deposited within hepatocellular carcinoma tissue and persists during treatment, resulting in an increase in Hounsfield units (HU) in the tumor area on CT images. In radiotherapy, the radiotherapy planning system converts the HU values ​​on CT images into relative electron density (RED) to calculate the dose distribution. Therefore, an increase in the HU value in the iodized oil area will alter the RED, leading to a change in the dose distribution. While existing studies have found that iodized oil affects the depth of proton radiotherapy beam irradiation, there is a lack of research on the effect of the iodized oil area on photon radiotherapy dose. Summary of the Invention

[0003] Therefore, the present invention aims to overcome the technical problems of the prior art, thereby providing a test system and method for the effect of iodized oil area on photon radiotherapy dose.

[0004] The present invention provides a test system for the effect of iodized oil area on photon radiotherapy dose, comprising:

[0005] There are multiple iodized oil samples, each of which is prepared by mixing minced pork liver and iodized oil in different proportions;

[0006] The sample tube is cylindrical and consists of several detachably connected sample chambers. The iodized oil samples are respectively placed in the sample chambers of the sample tube, and the sample chambers correspond to the iodized oil samples one by one.

[0007] A radiotherapy planning system, suitable for simulating photon beam irradiation of a sample tube and obtaining a simulated dose of electron density;

[0008] a linear accelerator suitable for irradiating the sample tube with the same photon beam as used in the radiotherapy planning system;

[0009] Ionization chamber detector is suitable for measuring the charge of iodized oil samples irradiated by linear accelerator to obtain the actual dose of electron density.

[0010] Furthermore, there were six iodized oil samples, and the mixing ratios of iodized oil and minced pork liver in the iodized oil samples were 0 ml / 100 g, 2 ml / 100 g, 5 ml / 100 g, 10 ml / 100 g, 15 ml / 100 g and 20 ml / 100 g, respectively.

[0011] Furthermore, an ionization chamber channel is provided through the middle position of the sample tube, and during detection, the ionization chamber detector is inserted into the ionization chamber channel;

[0012] The sample tube is made of PE material;

[0013] The sample chambers are sealed and connected to each other.

[0014] Furthermore, it also includes:

[0015] The sample tube is inserted into the abdomen simulation phantom, and the linear accelerator irradiates the abdomen simulation phantom with the sample tube inserted therein.

[0016] Furthermore, it also includes:

[0017] The CT scanner is suitable for scanning the abdominal simulation phantom to obtain a CT image. The CT scanner is connected to a radiotherapy planning system. The radiotherapy planning system simulates photon beam irradiation of the sample tube based on the CT image and obtains a simulated dose of electron density.

[0018] A test method for the effect of lipiodol area on photon radiotherapy dose, suitable for the test system for the effect of lipiodol area on photon radiotherapy dose, comprises the following steps:

[0019] S1, divide the six sample chambers storing iodized oil samples into two groups, and connect three sample chambers in each group into sample tubes;

[0020] S2, inserting the first set of sample tubes into an abdominal simulation phantom, and scanning the abdominal simulation phantom with a CT scanner to obtain a CT image;

[0021] S3, the radiotherapy planning system imports the CT image and simulates photon beam irradiation to the three sample chambers of the first group of sample tubes in the abdominal simulation phantom to obtain simulated doses of electron density in the three sample chambers;

[0022] In step S4, a linear accelerator is used to irradiate the three sample compartments of the first group of sample tubes in the abdominal simulation phantom with the same photon beam as that used in the radiotherapy planning system. The actual dose of electron density in the three sample compartments is obtained through the ionization chamber detector;

[0023] S5, inserting the second set of sample tubes into the abdomen simulation phantom, and repeating steps S2-S4.

[0024] Furthermore, the mixing ratios of iodized oil and minced pork liver in the three sample chambers of the first group of sample tubes are 0 ml / 100 g, 2 ml / 100 g, and 5 ml / 100 g, respectively.

[0025] Furthermore, the mixing ratios of iodized oil and minced pork liver in the three sample chambers of the second group of sample tubes were 10 ml / 100 g, 15 ml / 100 g, and 20 ml / 100 g, respectively.

[0026] Furthermore, when the ionization chamber detector obtains the actual dose of the electron density of the three sample chambers, the ionization chamber detector is located at the center of the sample chamber.

[0027] Furthermore, the CT image is respectively outlined with an iodized oil area, an ionization chamber detector and a normal tissue simulation organ.

[0028] The technical solution of the present invention has the following advantages:

[0029] The present invention provides a test system and method for evaluating the effect of an iodized oil area on photon radiotherapy dose. The linear accelerator irradiates an abdominal simulation phantom into which a sample tube is inserted. The CT scanner is connected to a radiotherapy planning system, which simulates photon beam irradiation of the sample tube based on CT images and obtains a simulated dose of electron density. The present application can compare the simulated dose of electron density obtained by the radiotherapy planning system with the actual dose of electron density obtained by an ionization chamber detector to characterize the effect of the iodized oil area on the photon radiotherapy dose. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Schematic diagram of the test method of the present invention;

[0032] Figure 2 Schematic diagram of the structure of the first group of sample tubes and the second group of sample tubes of the present invention;

[0033] Figure 3 Schematic diagram of the cross-sectional structure of the sample tube of the present invention;

[0034] Figure 4 This is a schematic diagram of the abdominal simulation phantom structure of the present invention;

[0035] Figure 5 CT images of the first group of sample tubes of the present invention;

[0036] Figure 6 This is the CT image of the second group of sample tubes of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0040] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Example

[0042] Liver cancer is the sixth most common malignant tumor and the third leading cause of cancer-related death worldwide, resulting in 830,000 deaths annually. In my country, liver cancer ranks fourth in incidence and second in mortality. Hepatocellular carcinoma (HCC) is the most common histological type of primary liver cancer, accounting for 75%-85% of cases. HCC presents insidiously, with 64% of patients in my country presenting at advanced stages at initial diagnosis. Transcatheter arterial chemoembolization (TACE) is an important treatment option. It is currently considered first-line therapy for HCC patients with BCLC stage B, good liver function, and no macroscopic vascular invasion or extrahepatic spread. However, TACE is not a curative treatment for most patients. Combining TACE with radiotherapy can significantly improve patient outcomes. Meta-analyses have shown that combined interventional therapy with radiotherapy significantly improves objective response rate (ORR) compared to interventional therapy alone, extending median survival from 13.5 months to 22.7 months.

[0043] After interventional therapy, iodized oil is specifically deposited within hepatocellular carcinoma tissue and persists during treatment, resulting in an increase in Hounsfield units (HU) in the tumor region on CT images. In photon radiotherapy, the radiotherapy planning system calculates dose distribution based on the conversion of HU values ​​from CT images to relative electron density (RED). Therefore, an increase in HU values ​​in the iodized oil region alters the RED, leading to a change in the dose distribution. Dongho Shin et al. evaluated the effect of iodized oil on the depth of proton therapy beam delivery and found that high HU values ​​in the iodized oil region resulted in a deeper beam depth, leading to an overestimation of the iodized oil's ability to block the proton beam by the radiotherapy planning system. This resulted in significantly greater actual doses delivered to the tumor region and organs at risk (OARs) than planned. Scherman et al. measured iodine-containing liquid markers used in lung proton radiotherapy and found that iodized oil markers can cause a 4.8% dose perturbation. In photon radiotherapy, the accuracy of photon dose calculations directly based on the converted RED by the radiotherapy planning system and the effect of lipiodol deposition on the photon beam dose are currently under investigation. Furthermore, previous studies have used pure lipiodol directly. Designing a system for simulating different lipiodol density areas after liver tumor intervention is crucial for clinical research.

[0044] like Figures 1 to 6 The present invention provides a specific embodiment of a test system and method for testing the effect of an iodized oil area on photon radiotherapy dose. The test system includes:

[0045] There are multiple iodized oil samples, each of which is prepared by mixing minced pork liver and iodized oil in different proportions;

[0046] The sample tube is cylindrical and consists of several detachably connected sample chambers. The iodized oil samples are respectively arranged in the sample chambers of the sample tube. The sample chambers correspond to the iodized oil samples one by one. The capacity of the sample chambers can be about 60 ml.

[0047] A radiotherapy planning system, suitable for simulating photon beam irradiation of a sample tube and obtaining a simulated dose of electron density;

[0048] a linear accelerator suitable for irradiating the sample tube with the same photon beam as used in the radiotherapy planning system;

[0049] Ionization chamber detector is suitable for measuring the charge of iodized oil samples irradiated by linear accelerator to obtain the actual dose of electron density.

[0050] Furthermore, there were six iodized oil samples, and the mixing ratios of iodized oil and minced pork liver in the iodized oil samples were 0 ml / 100 g, 2 ml / 100 g, 5 ml / 100 g, 10 ml / 100 g, 15 ml / 100 g and 20 ml / 100 g, respectively.

[0051] Furthermore, an ionization chamber channel is provided through the middle of the sample tube to facilitate CT scanning and dose measurement. During detection, the ionization chamber detector is inserted into the ionization chamber channel.

[0052] The sample tube is made of PE material;

[0053] The sample chambers are sealed and connected to each other.

[0054] Furthermore, it also includes:

[0055] The sample tube is inserted into the abdomen simulation phantom, and the linear accelerator irradiates the abdomen simulation phantom with the sample tube inserted therein.

[0056] Furthermore, it also includes:

[0057] The CT scanner is suitable for scanning the abdominal simulation phantom to obtain a CT image. The CT scanner is connected to a radiotherapy planning system. The radiotherapy planning system simulates photon beam irradiation of the sample tube based on the CT image and obtains a simulated dose of electron density.

[0058] A test method for the effect of lipiodol area on photon radiotherapy dose, suitable for the test system for the effect of lipiodol area on photon radiotherapy dose, comprises the following steps:

[0059] S1, divide the six sample chambers storing iodized oil samples into two groups, and connect three sample chambers in each group into sample tubes;

[0060] S2, inserting the first set of sample tubes into an abdominal simulation phantom, and scanning the abdominal simulation phantom with a CT scanner to obtain a CT image;

[0061] S3, the radiotherapy planning system imports the CT image and simulates photon beam irradiation to the three sample chambers of the first group of sample tubes in the abdominal simulation phantom to obtain simulated doses of electron density in the three sample chambers;

[0062] In step S4, a linear accelerator is used to irradiate the three sample compartments of the first group of sample tubes in the abdominal simulation phantom with the same photon beam as that used in the radiotherapy planning system. The actual dose of electron density in the three sample compartments is obtained through the ionization chamber detector;

[0063] S5, inserting the second set of sample tubes into the abdomen simulation phantom, and repeating steps S2-S4.

[0064] To avoid the differences in HU value definitions between different CT scanners and radiotherapy planning systems, this application has carried out accurate electron density calibration for lipiodol samples of different mixing ratios. This calibration density will serve as a standard reference for subsequent research. Sample tubes containing lipiodol samples are assembled in groups of three and inserted into the base of the abdominal simulation phantom; ionization chamber detectors are placed in the centers of each of the six sample bins, and a spiral CT scan (Siemens SOMATOM Definition AS CT) with a 1mm per layer is performed, with a scanning voltage of 120kV and a current of 300mA. The scanned CT images are uploaded to the connected radiotherapy planning system (Pinnacle3 V16.2), and the average RED of the lipiodol samples of different mixing ratios in each group is calibrated based on the HU-RED conversion relationship used by the radiotherapy planning system.

[0065] In the radiotherapy planning system, fixed 6MV X-rays, different fractionation modes (1 Gy / f–10 Gy / f) and uniform block mode (FF / FFF) can be used to irradiate iodized oil samples with different densities, and the simulated dose of electron density under the current radiotherapy planning system can be recorded.

[0066] The linear accelerator can implement the same beam irradiation as the radiotherapy planning system on the abdominal simulation phantom with the sample tube inserted. The ionization chamber charge number at the center of each sample chamber is read through the ionization chamber detector to record the actual dose of electron density in each mode.

[0067] Furthermore, the mixing ratios of iodized oil and minced pork liver in the three sample chambers of the first group of sample tubes are 0 ml / 100 g, 2 ml / 100 g, and 5 ml / 100 g, respectively.

[0068] Furthermore, the mixing ratios of iodized oil and minced pork liver in the three sample chambers of the second group of sample tubes were 10 ml / 100 g, 15 ml / 100 g, and 20 ml / 100 g, respectively.

[0069] Furthermore, when the ionization chamber detector obtains the actual dose of the electron density of the three sample chambers, the ionization chamber detector is located at the center of the sample chamber.

[0070] Furthermore, the CT image is respectively outlined with an lipiodol area, an ionization chamber detector, and a normal tissue simulation organ. The lipiodol area is the area where the lipiodol sample is located.

[0071] The present application can compare the simulated dose of electron density obtained by the radiotherapy planning system with the actual dose of electron density obtained by the ionization chamber detector to characterize the influence of the iodized oil area on the photon radiotherapy dose.

[0072] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A test method for the effect of lipiodol area on photon radiotherapy dose, characterized in that: include: The test system for the effect of iodized oil area on photon radiotherapy dose includes: There are multiple iodized oil samples, each of which is prepared by mixing minced pork liver and iodized oil in different proportions; The sample tube is cylindrical and consists of several detachably connected sample chambers. The iodized oil samples are respectively placed in the sample chambers of the sample tube, and the sample chambers correspond to the iodized oil samples one by one. A radiotherapy planning system, suitable for simulating photon beam irradiation of a sample tube and obtaining a simulated dose of electron density; a linear accelerator suitable for irradiating the sample tube with the same photon beam as used in the radiotherapy planning system; Ionization chamber detector, suitable for measuring the charge of iodized oil samples irradiated by linear accelerator to obtain the actual dose of electron density; There were six iodized oil samples, and the mixing ratios of iodized oil and minced pork liver in the iodized oil samples were 0 ml / 100 g, 2 ml / 100 g, 5 ml / 100 g, 10 ml / 100 g, 15 ml / 100 g, and 20 ml / 100 g, respectively; Also includes: an abdominal simulation phantom, wherein the sample tube is inserted into the abdominal simulation phantom, and the linear accelerator irradiates the abdominal simulation phantom with the sample tube inserted therein; Also includes: A CT scanner, adapted to scan the abdominal simulation phantom to obtain a CT image, the CT scanner being connected to a radiotherapy planning system, which simulates photon beam irradiation of the sample tube based on the CT image and obtains a simulated dose of electron density; The following steps are also included: S1, divide the six sample chambers storing iodized oil samples into two groups, and connect three sample chambers in each group into sample tubes; S2, inserting the first set of sample tubes into an abdominal simulation phantom, and scanning the abdominal simulation phantom with a CT scanner to obtain a CT image; S3, the radiotherapy planning system imports the CT image and simulates photon beam irradiation to the three sample chambers of the first group of sample tubes in the abdominal simulation phantom to obtain simulated doses of electron density in the three sample chambers; In step S4, a linear accelerator is used to irradiate the three sample compartments of the first group of sample tubes in the abdominal simulation phantom with the same photon beam as that used in the radiotherapy planning system. The actual dose of electron density in the three sample compartments is obtained through the ionization chamber detector; S5, inserting the second set of sample tubes into the abdomen simulation phantom, and repeating steps S2-S4.

2. The test method of the lipiodol zone on the photon radiotherapy dose influence according to claim 1, characterized in that, An ionization chamber channel is provided through the middle of the sample tube, and during detection, the ionization chamber detector is inserted into the ionization chamber channel; The sample tube is made of PE material; The sample chambers are sealed and connected to each other.

3. The test method of the lipiodol zone on the photon radiotherapy dose influence according to claim 1, wherein The mixing ratios of iodized oil and minced pork liver in the three sample chambers of the first group of sample tubes were 0 ml / 100 g, 2 ml / 100 g, and 5 ml / 100 g, respectively.

4. The test method of the lipiodol zone on the photon radiotherapy dose influence according to claim 1, wherein The mixing ratios of iodized oil and minced pork liver in the three sample chambers of the second group of sample tubes were 10 ml / 100 g, 15 ml / 100 g, and 20 ml / 100 g, respectively.

5. The test method of the lipiodol area on the photon radiotherapy dose effect according to claim 1, characterized in that, When the ionization chamber detector obtains actual doses of electron density in three sample chambers, the ionization chamber detector is located at the center of the sample chamber.

6. The test method of the lipiodol area on the photon radiotherapy dose effect according to claim 5, characterized in that, The CT image is respectively outlined with an iodized oil area, an ionization chamber detector, and a normal tissue simulation organ.

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