Radiotherapy field arrangement method and system for esophageal cancer T-shaped target region

Abstract

The application discloses a radiotherapy field arrangement method and system for esophageal cancer T-shaped target area, comprising: obtaining medical image data of an esophageal cancer patient, extracting three-dimensional contour data of the T-shaped target area, the T-shaped target area comprising an upper target area and a lower target area; setting seven coplanar fixed fields and gantry angles; for the fields with the gantry angles of 200°, 320°, 0°, 40° and 160°, rotating the collimator to make the movement direction of the multileaf collimator blade perpendicular to the extension direction of the target area, and locking the lead door to cover only the proximal target area; for the fields with the gantry angles of 280° and 80°, locking the lead door to cover only the upper target area. The application realizes the lung protection effect equivalent to the 12-field segmented scheme in a single 7-field plan through field division and geometric matching, significantly reduces the machine jump number and treatment time, and balances the lung protection and treatment efficiency.

Description

Technical Field

[0001] This invention relates to the field of tumor radiotherapy technology, specifically to a method and system for radiotherapy field arrangement in esophageal cancer, particularly suitable for radiotherapy planning of T-type target areas in esophageal cancer involving the risk of cervical lymph node metastasis. Background Technology

[0002] Esophageal cancer is one of the most common malignant tumors worldwide. Clinically, esophageal cancer diagnosed during physical examinations or checkups is often already in the middle or late stages. In terms of location, most esophageal cancers are located in the upper or lower thoracic region, with some cases showing a risk of cervical lymph node metastasis.

[0003] Currently, the main treatments for esophageal cancer include surgery, chemotherapy, and radiation therapy. While radiation therapy uses rays to kill tumor cells, it inevitably causes damage to surrounding normal organs (such as the lungs, heart, and spinal cord). Therefore, when developing a radiation therapy plan, physicists must consider how to improve the tumor control rate (TCP) while reducing the probability of non-TCP complications in normal tissues.

[0004] For esophageal cancer target areas with a risk of cervical lymph node metastasis (commonly known as T-type tumor target areas), conventional radiation field arrangements often result in a large area of ​​the lungs receiving low-dose radiation, increasing the risk of radiation pneumonitis. While existing technologies can reduce lung dose by increasing the number of radiation fields and using lead gates in different areas, these methods suffer from problems such as excessively long treatment times, excessive machine jumps (MUs), and low clinical implementation efficiency. Therefore, there is an urgent need for a radiation field arrangement scheme that can effectively protect normal tissues while also being clinically feasible. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for radiotherapy field arrangement for T-type target areas of esophageal cancer, aiming to solve the technical problem in the prior art that it is difficult to balance low-dose protection of the lungs and treatment efficiency during T-type target area radiotherapy for esophageal cancer.

[0006] The present invention provides a method for radiotherapy field arrangement in the T-type target area of ​​esophageal cancer, comprising the following steps:

[0007] Acquire target area contour data: Acquire medical imaging data of esophageal cancer patients and extract three-dimensional contour data of T-shaped target areas from the medical imaging data. The T-shaped target areas include the upper target area corresponding to the high-risk area of ​​cervical lymph node metastasis and the lower target area corresponding to the primary lesion area of ​​the esophagus.

[0008] Set coplanar firing field parameters: Set 7 coplanar firing fields, with frame angles of 200°, 280°, 320°, 0°, 40°, 80° and 160° for each field respectively;

[0009] Collimator rotation and lead door locking for the first type of firing field: For firing fields with frame angles of 200°, 320°, 0°, 40° and 160°, the collimator angle is rotated so that the direction of movement of the multi-leaf collimator blades is perpendicular to the extension direction of the T-shaped target area, and the lead door position is locked to block the far target area so that the irradiation range only covers the near target area.

[0010] The second type of firing field is treated with lead door locking: For firing fields with frame angles of 280° and 80°, the lead door position is locked so that the irradiation range only covers the upper target area, while the lower target area is not irradiated.

[0011] Furthermore, the radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer also includes: setting optimization constraints in the planning system, the optimization constraints including target area dose constraints, organ at risk dose limits and auxiliary annular constraint areas, determining the position of the multi-leaf collimator blades, the irradiation dose weight and the total number of machine jumps for each field through iterative optimization calculation, and generating the final field parameter configuration.

[0012] Furthermore, the auxiliary ring structure is located 2mm from the outer edge of the target area and has a width of 15mm, which is used to constrain the high-dose line to be close to the target area boundary during the optimization process.

[0013] Furthermore, the target volume dose constraint is that 100% of the prescribed dose covers 95% of the target volume, and the organ at risk dose limit includes lung V5 < 60%.

[0014] Furthermore, the method for arranging the radiotherapy field for the T-type target area of ​​esophageal cancer also includes setting the dose rate of the field to 400 MU / min and the radiation energy to 6 MV.

[0015] The present invention also discloses a radiotherapy field arrangement system, which includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer.

[0016] The present invention also discloses a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for radiotherapy field arrangement for a T-shaped target area of ​​esophageal cancer.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention divides seven coplanar fixed fields into two groups of radiation fields with different functions. For the first type of radiation field, the collimator is rotated so that the movement direction of the multi-leaf collimator blades is perpendicular to the extension direction of the target area, and then a lead gate is locked to block the distal target area, covering only the proximal target area. For the second type of radiation field, the lead gate is directly locked to irradiate only the upper section of the target area. This achieves selective and differentiated irradiation of the upper and lower sections, as well as the proximal and distal sides of the T-shaped target area.

[0019] Compared to the conventional 7-field fully open lead-gate approach, this invention effectively reduces the volume of lung tissue exposed to low-dose radiation. Example data shows that the lung V5 of this invention is 54.7%, significantly lower than the conventional approach's 65.1%, meeting the clinical limit requirement (V5 < 60%), thereby effectively reducing the risk of radiation pneumonitis.

[0020] Meanwhile, compared to the 12-field approach that completely divides the target area into upper and lower target areas and deploys them separately, this invention uses only 7 firing fields. Through the division of firing fields within the same plan, it achieves a comparable effect of normal organ protection as the 12-field approach. Example data shows that the machine hop count of this invention is only 907 hops, approximately 63.3% of the 12-field approach (1433 hops), significantly shortening treatment time. This not only improves patient tolerance and departmental efficiency but also reduces the mechanical wear and tear on the accelerator.

[0021] 2. This invention reduces low-dose irradiation of the lungs without sacrificing the quality of target area dose coverage. Example data shows that the prescription of this invention achieves 100% dose coverage of 95% of the target volume, and the maximum target dose, average dose, conformity index, and homogeneity index are not statistically significantly different from the complex 12-field segmentation scheme, ensuring effective tumor control.

[0022] 3. This invention does not require complex multi-segment plan fusion or additional plan splicing operations. Selective irradiation of the T-shaped target area can be achieved in a single plan by coordinating the rotating collimator and the locking lead gate, which has good clinical operability and promotion prospects. Attached Figure Description

[0023] Figure 1 3D image of the T-shaped target region for esophageal cancer;

[0024] Figure 2 Schematic diagram of a rotating collimator;

[0025] Figure 3 Schematic diagram of rotating collimator and lead lock door;

[0026] Figure 4 Diagram of a lead-locked door;

[0027] Figure 5 A schematic diagram of the anatomical location of the T-shaped target area for esophageal cancer on a coronal CT scan.

[0028] Figure 6 Schematic diagram of a rotating collimator on a coronal CT section of a T-type target area;

[0029] Figure 7 Schematic diagram of a lead door locked on a coronal CT cross-section of the T-type target area;

[0030] Figure 8 Transverse view of the target area - CT cross section of the neck.

[0031] Figure 9 This is a schematic diagram of the 320° firing field;

[0032] Figure 10 This is a schematic diagram of proximal irradiation. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] The radiotherapy field setup method for the T-type target area of ​​esophageal cancer in this embodiment includes the following steps:

[0035] Acquire target area contour data: Acquire medical imaging data of esophageal cancer patients, and extract three-dimensional contour data of T-shaped target areas from the medical imaging data. The T-shaped target areas include the upper target area corresponding to the high-risk area of ​​cervical lymph node metastasis and the lower target area corresponding to the primary lesion area of ​​the esophagus.

[0036] Set coplanar firing field parameters: Set 7 coplanar firing fields, with frame angles of 200°, 280°, 320°, 0°, 40°, 80° and 160° for each field.

[0037] Collimator rotation and lead door locking for the first type of firing field: For firing fields with frame angles of 200°, 320°, 0°, 40° and 160°, the collimator angle is rotated so that the direction of movement of the multi-leaf collimator blades is perpendicular to the extension direction of the T-shaped target area, and the lead door position is locked to block the far target area so that the irradiation range only covers the near target area.

[0038] The second type of firing field is treated with lead door locking: For firing fields with frame angles of 280° and 80°, the lead door position is locked so that the irradiation range only covers the upper target area, while the lower target area is not irradiated.

[0039] As an improvement to the above embodiments, the radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer further includes: setting optimization constraints in the planning system, the optimization constraints including target area dose constraints, organ at risk dose limits and auxiliary annular constraint areas, determining the position of the multi-leaf collimator blades, the irradiation dose weight and the total number of machine jumps for each field through iterative optimization calculation, and generating the final field parameter configuration.

[0040] As an improvement to the above embodiment, the auxiliary ring structure is located 2mm from the outer edge of the target area and has a width of 15mm, which is used to constrain the high-dose line to be close to the target area boundary during the optimization process.

[0041] As an improvement to the above embodiments, the target volume dose constraint condition is that 100% of the prescribed dose covers 95% of the target volume, and the organ at risk dose limit condition includes lung V5 < 60%.

[0042] As an improvement to the above embodiments, the radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer further includes setting the dose rate of the field to 400 MU / min and the radiation energy to 6 MV.

[0043] The advantages of the method described in this embodiment are illustrated below by comparing it with existing technologies:

[0044] I. Case Information

[0045] One patient with esophageal cancer at risk of cervical lymph node metastasis was selected. CT scan showed lesions extending from the mid-chest to the neck, clinically stage III (T3N1M0). The prescribed dose was 59.4 Gy / 33F. The patient's lung volume was 4111.5 cc, heart volume was 649.8 cc, and target volume was 536 cc.

[0046] II. Planning System and Equipment

[0047] A Varian IX linear accelerator was used, equipped with a 120-leaf multi-leaf collimator (40 pairs of leaves in the middle, each 5 mm wide, and 20 pairs of leaves on each side, each 10 mm wide). The maximum range of the X / Y direction lead gate was 20 cm × 20 cm, and the lead gate did not have an automatic following function. The planning system version was Eclipse v15.6, the dose algorithm was anisotropic analytical algorithm (AAA), the dose rate was 400 MU / min, and the radiation energy was 6 MV.

[0048] III. Auxiliary Structure Settings

[0049] An auxiliary annular constraint zone with a width of 15 mm was set 2 mm outside the target area, and the optimization weight was set to high to constrain the dose drop rate around the target area and protect the adjacent normal tissue.

[0050] IV. Scheme Setting

[0051] Option 1 (Standard Option):

[0052] Seven coplanar fixed fields are used, with frame angles of 200°, 280°, 320°, 0°, 40°, 80°, and 160°. The lead door is fully open, without locking the lead door or rotating the collimator.

[0053] Option 2 (Partial Jungle Locking Strategy):

[0054] Seven coplanar fixed fields are used, with frame angles of 200°, 280°, 320°, 0°, 40°, 80°, and 160°. At frame angles of 200°, 320°, 0°, 40°, and 160°, the lead door is fully open; at frame angles of 280° and 80°, the lead door is locked, ensuring the irradiation range covers only the upper part of the target area; the collimator is not rotated at any frame angle.

[0055] Option 3 (Multi-field approach with segmented target area):

[0056] The target area was divided into an upper target area and a lower target area, with separate firing fields. The upper target area used 7 firing fields with frame angles of 200°, 280°, 320°, 0°, 40°, 80°, and 160°, with the lead door locked to illuminate only the upper target area. The lower target area used 5 firing fields with frame angles of 200°, 320°, 0°, 40°, and 160°, with the lead door locked to illuminate only the lower target area. A total of 12 firing fields were used.

[0057] Option 4 (Invention Solution):

[0058] Seven coplanar fixed fields were employed, with frame angles of 200°, 280°, 320°, 0°, 40°, 80°, and 160°. For the fields with frame angles of 280° and 80°, the lead door was locked, ensuring the irradiation range covered only the upper target area. For the fields with frame angles of 200°, 320°, 0°, 40°, and 160°, the collimator angle was rotated so that the blades of the multi-leaf collimator moved perpendicular to the extension direction of the T-shaped target area, and the lead door position was locked to block the distant target area, ensuring the irradiation range covered only the near target area.

[0059] V. Dosimetric Results

[0060] Target volume dose: All four regimens met clinical requirements, namely, 100% of the prescribed dose covered 95% of the target volume, and there were no statistically significant differences in the maximum dose, average dose, conformity index, and homogeneity index of the target volume.

[0061] Organ-risk dose:

[0062] Option 1: Lung V5 is 65.1%, exceeding the clinical limit (V5<60%), indicating a large low-dose zone;

[0063] Option 2: Lung V5 decreased to 61.5% compared to Option 1, showing some improvement, but still did not meet clinical requirements;

[0064] Option 3: Lung V5 was the lowest at 54.3%, but the number of MUs was the highest (1433 jumps) and the treatment time was the longest;

[0065] Option 4: Lung V5 was 54.7, which was basically the same as Option 3 (p>0.05), but the number of MUs was 907, which was about 63.3% of Option 3, and the treatment time was significantly shortened.

[0066] The cardiac and spinal cord dosages in all four regimens met clinical requirements with little difference.

[0067] VI. Conclusion

[0068] The field arrangement method (Scheme 4) proposed in this invention achieves the same excellent protection of normal organs as the complex segmented field arrangement (Scheme 3) while ensuring the target dose, and significantly simplifies the planning complexity and improves treatment efficiency. This method has high practical value and promotion significance in clinical T-type target radiotherapy for esophageal cancer.

[0069] Example 2: A radiotherapy field arrangement system includes a processor and a memory. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the radiotherapy field arrangement method for the T-shaped target area of ​​esophageal cancer as described in Example 1.

[0070] Example 3: A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the radiotherapy field arrangement method for the T-shaped target area of ​​esophageal cancer as described in Example 1.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for radiotherapy field arrangement in a T-type target area for esophageal cancer, characterized in that: Includes the following steps: Acquire target area contour data: Acquire medical imaging data of esophageal cancer patients and extract three-dimensional contour data of T-shaped target areas from the medical imaging data. The T-shaped target areas include the upper target area corresponding to the high-risk area of ​​cervical lymph node metastasis and the lower target area corresponding to the primary lesion area of ​​the esophagus. Set coplanar firing field parameters: Set 7 coplanar firing fields, with frame angles of 200°, 280°, 320°, 0°, 40°, 80° and 160° for each field respectively; Collimator rotation and lead door locking for the first type of firing field: For firing fields with frame angles of 200°, 320°, 0°, 40° and 160°, the collimator angle is rotated so that the direction of movement of the multi-leaf collimator blades is perpendicular to the extension direction of the T-shaped target area, and the lead door position is locked to block the far target area so that the irradiation range only covers the near target area. The second type of firing field is treated with lead door locking: For firing fields with frame angles of 280° and 80°, the lead door position is locked so that the irradiation range only covers the upper target area, while the lower target area is not irradiated.

2. The method for radiotherapy field arrangement for T-type target areas of esophageal cancer according to claim 1, characterized in that: Also includes: The planning system sets optimization constraints, including target area dose constraints, organ-at-risk dose limits, and auxiliary annular constraint areas. The position of the multi-leaf collimator blades, the irradiation dose weight, and the total number of machine jumps for each radiation field are determined through iterative optimization calculations, generating the final radiation field parameter configuration.

3. The method for radiotherapy field arrangement for T-type target areas of esophageal cancer according to claim 2, characterized in that: The auxiliary ring structure is located 2mm from the outer edge of the target area and has a width of 15mm. It is used to constrain the high-dose line to be close to the target area boundary during the optimization process.

4. The method for radiotherapy field arrangement for T-type target areas of esophageal cancer according to claim 2, characterized in that: The target volume dose constraint is that 100% of the prescribed dose covers 95% of the target volume, and the organ at risk dose limit includes lung V5 < 60%.

5. The method for radiotherapy field arrangement for T-type target areas of esophageal cancer according to claim 1, characterized in that: It also includes setting the dose rate of the radiation field to 400 MU / min and the X-ray energy to 6 MV.

6. A radiotherapy field layout system, characterized in that, It includes a processor and a memory, the memory storing a computer program, and the processor executing the computer program to implement the steps of the radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer as described in any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the radiotherapy field arrangement method for the T-type target area of ​​esophageal cancer as described in any one of claims 1 to 5.

Images